Exceeding that recommendation can cause health problems. If you’re having more than 500 mg of caffeine in a day, you may have trouble sleeping, upset stomach, irritability, an irregular heartbeat, or tremors.

Elenkiwich said the limit on caffeine may be higher or lower depending on the person.

“It’s not a part of the USDA dietary guidelines so it’s kind of like any other supplement,” she said. “Going over 500 (mg) may really hinder some people’s sleep, but others might be so accustomed to it that it won’t affect them.”

On the WCCO-TV website, Sara Huffman commented, “it’s too much (caffeine) when you begin to rely on it to keep you alert…coffee is just part of my daily routine.”

Women who are pregnant should consume less caffeine — under 200 mg a day. Exceeding that amount puts them at greater risk for miscarriage.

While getting some caffeine is good for us, health officials say don’t try to pass off that Mountain Dew as a drink for your health. A study from the American Journal of Clinical Nutrition showed that regular soda drinkers had an increased risk of type 2 diabetes, whereas diet soda drinkers had no increased risk and coffee drinkers had a lower risk.

“It’s really a matter of looking at where your calories and sugar are coming from, where you’re getting your caffeine,” Elenkiwich said.

A Starbucks vanilla frappuccino with whip cream packs in 20 percent of the USDA calorie requirement. So, if you want your caffeine fix and a way to benefit your health, stick to a cup of coffee that’s easy on the sugar.